An arterial aneurysm is a localized enlargement of an artery. Cerebral aneurysms or rather intracranial aneurysms (aneurysms of brain vessels), are “balloon-like” protrusion of intracranial arteries characterized by an opening (“neck”) that feeds into an enlarged capsular structure (“dome”).
The rupture of an intracranial aneurysm is a severe event that may potentially lead to severe disability or death.
Aneurysms (i.e. arterial malformations) especially in the brain are treated more and more by using minimal invasive approaches instead of open brain surgery. With reference to FIG. 1 a three-dimensional angiography of an aneurysm A in the brain is shown. It is possible, that the angiography is automatically processed to extract centerlines, diameters, aneurysm dome height etc. of the aneurysm and the surrounding vessels, in particular the parent vessel PV. With the minimal invasive approach, a catheter is brought through the arterial system of the patient to the aneurysm, through which small coils can be applied. The aneurysm is now treated by filling it subsequently with coils until the blood flow inside it is blocked and a thrombus is formed. Various types of coils are used for embolization of aneurysms including bare metal platinum and hydrocoils. It is advantageous that not only the aneurysm is sufficiently filled with coils to induce a thrombus, but also to ensure that the coils do not reach into the parent artery in order to minimize the risk of thrombosis formation inside the artery itself.
With reference to FIG. 2 an aneurysm A and the corresponding parent vessel PV is schematically shown. On the left hand side a) there is a view along the vessel, whereas on the right hand side b) there is a view from the side.
If the aneurysms neck N is not narrow, a stent is often placed to remodel the vessel end ensure that the coils stay inside the aneurysm.
According to US 2006/0184066 a method is used to support the previously mentioned stent placement. According to this method a surface model of an intracranial aneurysm in an artery is created, the aneurysm having a lumen, a neck and a dome. The method comprises steps of segmentation and analysis, in particular    computing centerline of the blood vessels and    aneurysm analysis like determining diameter and dome height.
With reference to FIG. 3 the above introduced information can be used to calculate properties of a virtual stent VS which optimally remodels the vessel. According to this information, a proper “real” stent can be chosen to treat the lesion.
Usually the coils form little baskets of different sizes (depending on the size of the coil, which is related to the highest curvature a coil can take). For larger aneurysms, multiple coils may have to be placed each one fitting into the previous placed coil. Therefore each aneurysm requires a careful choice of coils and the sequence of placement. For the treatment planning the physician has to decide which coils should be used in which order.